ISO 10303-22 is a part of the implementation methods of STEP with the official title Standard data access interface or simply SDAI.
The original intent of SDAI and its bindings to programming languages was to achieve portability of software applications from one implementation to another. This was soon abandoned because there were only a few commercial implementations and they differed significantly in their detailed APIs. Today the term SDAI is sometimes used for all kinds of APIs supporting STEP, even if they only partially follow the strict functionality as defined in ISO 10303-22 and its implementation methods, or not at all. Part 35 of STEP (Abstract test methods for SDAI implementations) provides a formal way how to prove the conformance of an implementation with SDAI.
The main components of SDAI are:
The NIST STEP Class Library is a public domain implementation of ISO 10303-21(ASCII data exchange files), -22(SDAI), -23 (C++ SDAI binding) using ISO 10303-11:1994. The development of the NIST STEP Class Library has been stopped in the late 1990s. SCL has been improved by the BRL-CAD developers and on github under the BSD license. SCL also has an experimental Python binding.